# -*- coding: utf-8 -*-

# Define here the models for your spider middleware
#
# See documentation in:
# https://doc.scrapy.org/en/latest/topics/spider-middleware.html

from scrapy import signals


class ArticlespiderSpiderMiddleware(object):
    # Not all methods need to be defined. If a method is not defined,
    # scrapy acts as if the spider middleware does not modify the
    # passed objects.

    @classmethod
    def from_crawler(cls, crawler):
        # This method is used by Scrapy to create your spiders.
        s = cls()
        crawler.signals.connect(s.spider_opened, signal=signals.spider_opened)
        return s

    def process_spider_input(self, response, spider):
        # Called for each response that goes through the spider
        # middleware and into the spider.

        # Should return None or raise an exception.
        return None

    def process_spider_output(self, response, result, spider):
        # Called with the results returned from the Spider, after
        # it has processed the response.

        # Must return an iterable of Request, dict or Item objects.
        for i in result:
            yield i

    def process_spider_exception(self, response, exception, spider):
        # Called when a spider or process_spider_input() method
        # (from other spider middleware) raises an exception.

        # Should return either None or an iterable of Response, dict
        # or Item objects.
        pass

    def process_start_requests(self, start_requests, spider):
        # Called with the start requests of the spider, and works
        # similarly to the process_spider_output() method, except
        # that it doesn’t have a response associated.

        # Must return only requests (not items).
        for r in start_requests:
            yield r

    def spider_opened(self, spider):
        spider.logger.info('Spider opened: %s' % spider.name)


class ArticlespiderDownloaderMiddleware(object):
    # Not all methods need to be defined. If a method is not defined,
    # scrapy acts as if the downloader middleware does not modify the
    # passed objects.

    @classmethod
    def from_crawler(cls, crawler):
        # This method is used by Scrapy to create your spiders.
        s = cls()
        crawler.signals.connect(s.spider_opened, signal=signals.spider_opened)
        return s

    def process_request(self, request, spider):
        # Called for each request that goes through the downloader
        # middleware.

        # Must either:
        # - return None: continue processing this request
        # - or return a Response object
        # - or return a Request object
        # - or raise IgnoreRequest: process_exception() methods of
        #   installed downloader middleware will be called
        return None

    def process_response(self, request, response, spider):
        # Called with the response returned from the downloader.

        # Must either;
        # - return a Response object
        # - return a Request object
        # - or raise IgnoreRequest
        return response

    def process_exception(self, request, exception, spider):
        # Called when a download handler or a process_request()
        # (from other downloader middleware) raises an exception.

        # Must either:
        # - return None: continue processing this exception
        # - return a Response object: stops process_exception() chain
        # - return a Request object: stops process_exception() chain
        pass

    def spider_opened(self, spider):
        spider.logger.info('Spider opened: %s' % spider.name)

from selenium import webdriver
from scrapy.http import HtmlResponse
import re
import time
class JSPageMiddelware(object):

    def process_request(self, request , spider):
        if spider.name == "sinanews":
            pattern = re.compile(u'/china/')
            print("访问:{0}".format(request.url))
            spider.browser.get(request.url)
            time.sleep(3)
            if (pattern.search(spider.browser.current_url)):
                # spider.browser.get(request.url)

                # 对于列表页进行下滑
                for i in range(3):
                    spider.browser.execute_script(
                        "window.scrollTo(0,document.body.scrollHeight); var lenOfPage=document.body.scrollHeight; return lenOfPage;")
                    time.sleep(3)
            return HtmlResponse(url=spider.browser.current_url,body=spider.browser.page_source, encoding="utf-8", request=request)
            # spider.browser.get(request.url)
            # import time
            # time.sleep(3)


            # pattern = re.compile(u'/china/')
            # if (pattern.search(spider.browser.current_url)):
            #
            #     for i in range(3):
            #         spider.browser.execute_script(
            #             "window.scrollTo(0,document.body.scrollHeight); var lenOfPage=document.body.scrollHeight; return lenOfPage;")
            #         time.sleep(3)
            # return HtmlResponse(url=spider.browser.current_url,body=spider.browser.page_source, encoding="utf-8", request=request)


#随机切换useragent
from fake_useragent import UserAgent

class RandomUserAgentMiddleware(object):
    def __init__(self,crawler):
        super(RandomUserAgentMiddleware,self).__init__()
        self.ua = UserAgent()


    @classmethod
    def from_crawler(cls,crawler):
        return cls(crawler)

    def process_request(self,request,spider):
        user_agent = self.ua.random
        request.headers.setdefault('User-Agent',self.ua.random)
